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serjou
Asked:2020-09-27 13:05:35 +0000 UTC2020-09-27 13:05:35 +0000 UTC

选择两个 ListView 项时如何激活按钮？WPF

  • 772

有一个 ListView 和一个按钮来比较两个项目，当两个项目被选中时，这两个项目应该是活动的。有这个XAML代码：

<Button Command="{Binding CompareSnapshots}"
    CommandParameter="{Binding SelectedItems, ElementName=SnapshotsListView}"
    IsEnabled="{Binding SelectedItems, ElementName=SnapshotsListView, Converter={StaticResource selectedItemCollectionToBoolConverter}}"
    Content="Compare"
    HorizontalAlignment="Stretch"
    VerticalAlignment="Top"
    Margin="0,10,0,0"
    Width="130"
    Height="60"
    Grid.Column="1"/>

转换器：

class SelectedItemCollectionToBoolConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        if (((IList<object>)value).Count == 2)
            return true;
        else
            return false;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

问题是绑定仅在应用程序启动时才有效。怎么修？

c#

1 个回答

  1. Best Answer

    XAML：

    <Button Command="{Binding CompareSnapshots}"
    CommandParameter="{Binding SelectedItems, ElementName=SnapshotsListView}"
    IsEnabled="{Binding SelectedItems.Count, ElementName=SnapshotsListView, Converter={StaticResource selectedItemCollectionToBoolConverter}}"
    Content="Compare"
    HorizontalAlignment="Stretch"
    VerticalAlignment="Top"
    Margin="0,10,0,0"
    Width="130"
    Height="60"
    Grid.Column="1"/>

    转换器：

    class SelectedItemCollectionToBoolConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return (int)value == 2;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}
    • 1

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